Hillary Clinton broke her silence on the FBI’s investigation into her email system Friday, arguing FBI Director James Comey had simply been “speculating” when he testified before Congress that her private server was likely hacked by hostile agents.

“I just believed that the material that was being communicated by professionals … they did not believe that it was [classified],” Clinton said during an interview with CNN’s Wolf Blitzer. “I did not have a basis for second-guessing their conclusion and these [emails] were not marked. They were not marked.”